Casting layer of apparatus for the manufacture of photographic film supports



FACTURE June 26, 1951 s. P. HENDRICX CASTING LAYER OF APPARATUS FOR THE MANU OF PHOTOGRAPHIC FILM SUPPORTS Filed Oct. 17, 1949 l :2. A: t. kw

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III/v ezviroz n eifi L cx Patented June 26, 1951 CASTING MANUFACTURE surron'rs Serge P. Hendricx,

signor to Gevaert Photo sel, Belgium, a Belgian company Application In the My invention relates to a support of preferably a drumor band casting machine, to which support is applied a casting layer consisting of cellulose derivatives.

Films and sheets usually are manufactured by spreading the film-forming solution upon a rotating drum, or moving endless band, of a casting machine. At first, the film-forming solution was directly spread upon a high-glossmetal surface. The smooth metal surface, however, is easily attacked whereby the film is more difficultly detached from the damaged places, which gives rise to matte surfaces. The support then must be repolished which is rather expensive. Moreover, when detaching the film from the metal surface, electrostatic charges easily arise, which for inflammable solvents increases the risk of fire.

In order to eliminate these disadvantages, the metal surface of the drum, respectively of the band, has been coated with a so-called casting layer which, when damaged or worn, easily may 7 be removed.

Many substances have been proposed for that purpose. One of the oldest means used as the casting layer is gelatine. Such as casting layer, however, has the disadvantage of quickly becoming brittle by the incessant contact with the organic solvents of the film-forming solutions and consequently must be renewed frequently.

It is further known that, when casting films from special cellulose derivatives, casting layers are used which consist of other cellulose derivatives, for instance cellulose ethers insoluble in the solvents used for the film to be cast.

It is also known to use in casting layers hydrophobic cellulose esters which contain radicals of fatty acids with more than 10 carbon atoms.

These casting layers, however, are never quite indifferent to the solvents used, but swell therein to some degree whereby the film in most cases is not readily detached from the casting layer.

It has further been proposed to use as a casting layer ethers of polysaccharides with glycolic acid and/or homologues of this acid and/or functional derivatives thereof. They had, however, the disadvantage that one was confined to special solvents for the substances from which the casting layer is coated.

In order to render the casting layer indifferent to the solvents, a casting layer consisting of cellulose esters was superficially saponified after being applied to the drum or band of the casting machine. This method had the disadvantage that after drying the superficial saponification and the further washing of the casting LAYER OF APPARATUS FOR THE OF PHOTOGRAPHIC FILM Mortsel-Antwerp, Belgium, as-

-Producten N. V., Mort- October 17, 1949, Serial No. 121,824 Netherlands October 30, 1948 4 Claims. (Cl. 1847) layer took much time and trouble. Moreover,

since the casting layer does not consist of a homogeneous substance, unexpected difficulties ar1se.

It is an object of my invention to cover the drum or band of a casting machine for the manufacture of photographic film supports with a casting layer of a special cellulose mixed ester compound.

It is another object of my invention to provide high-gloss casting layers from which the filmforming substances are easily detached.

Still another object of my invention is to obtain perfect high-gloss films used as support for photographic emulsions.

A particular object of my invention is to render the casting layer indifferent to a much larger number of organic solvents used in the preparation of dopes for the casting of photographic films.

Other objects will appear from the following description.

The above objects are accomplished according to the present invention by using as a casting layer on drums and bands of casting machines well-defined mixed cellulose esters, namely cellulose aceto-formate saponified to a suitable extent and containing acetyl and formyl groups in a well defined relation.

My invention resides in the discovery that from partially hydrolysed cellulose aceto-formate, having an acetyl content of between 14.4% and 32% and a formyl content of between 3% and 15% as further described, casting layers may be coated on drumand band casting machines, possessing a perfect high gloss and being indifferent to most organic solvent so that filmforming dopes of various compositions may be cast on it, leaving, without difficulties, film with a perfect high gloss.

The accompanying drawing is a diagrammatic representation of the cellulose aceto-formates which may be used as casting layers in accordance with the invention.

The left hand border of the diagram represents pure cellulose acetate with different percentages of esterification. The right hand border of the diagram represents pure cellulose formate with different percentages of esterification. The line connecting 44.8% acetyl with 35% formyl represents all fully esterified mixed cellulose acetoformates. The region above represents all possible not fully esterified cellulose aceto-formates. The area A B C D represents the partially esterified cellulose aceto-formates which may be used as a casting layer according to my present invention:

These cellulose aceto-formates, esterified up to 1 about 80% with an acetyl content of 14.-4--32% and a formyl content of 345%, further ofier the great advantage of dissolving quite well in aqueous mixtures of several organic solvents as for instance acetone, dioxane, ethyl lactate, ethylenechlorohydrine and the like. They provide a clear dope and may readily be coated. l'he proportion of the several ingredients in the solvents may thus be chosen that no noxious influence of the water present is observed while drying.

The casting layer thus obtained possesses a good high gloss and is very stable and indifferent to the usual organic solvents wherein the film-forming substances are dissolved so that the cast film is readily detached from the casting layer.

Example 1.--A cellulose aceto-formate, having an acetyl content by weight of the total mixed cellulose ester of 22.6% and a formyl content of 9% (point I of the accompanying drawing) is dissolved in a mixture of acetone, Water and dioxane, in a volume-proportion of 40:20:40, respectively. In the known manner, this solution is coated on an endless band. The casting layer dries up quite glossy and is ready for use. On this casting layer is coated a film-forming solution, consisting of cellulose diaoetate dissolved in acetone. After evaporation of the greater part of the solvent, the film is readily detached from this casting layer.

Example 2.A cellulose aceto-formate, having an acetyl content by Weight of the total mixed cellulose ester of 17.3% and a formyl content of 8.3% (point II of the accompanying drawing), is dissolved in a mixture of acetone, water, dioxane and ethyl lactate, respectively in a volume-proportion of 30:20:40z10. In the known manner, this solution is coated on an endless band. On this high-gloss casting layer is cast a film-forming solution, consisting of cellulose aceto-butyrate dissolved in a mixture of dichloromethane and ethanol in a volume-proportion of 90:10. After partly drying, the cellulose aceto-butyrate film is quite easily detached from the casting layer. The film possesses a high gloss.

Example 3.A cellulose aceto-formate, having an acetyl content by weight of the total mixed cellulose ester of 19% and a formyl content of 4.5% (point III of the accompanying drawing); is dissolved in a mixture of acetone, water, dioxane and chloro-hydroxy-2-ethane, in a volume-proportion of 30:20:40:10. In the known manner, a casting layer is made of this solution on an endless metal band. After drying, the casting layer shows a strong high gloss. On this casting layer is coated a cellulose nitrate support the solvent of which consists of a mixture of ethanol and ether in a volume-proportion of 1:1.5. The cellulose nitrate film support, after evaporation of the greater part of the solvent is quite easily detached with high gloss from the cellulose acetoformate casting layer.

Example 4.--A cellulose aceto-formate, having an acetyl content by weight of the total mixed cellulose ester of 27.5% and a formyl content of 5.5% (point IV of the accompanying drawing) is dissolved in a mixture of acetone, Water, and dioxane, respectively in a volume-proportion of 45:15:40. In the known manner, this solution is coated as casting layer on an endless band. After drying, this casting layer shows a perfect high gloss. Next, a film-forming solution consisting of cellulose aceto-propionate dissolved in a mixture of dichloromethane and methanol in a volume-proportion of 90:10 is coated thereon. 'After evaporation of the greater part of the solvent, the high-gloss aceto-propionat film is readily detached from the casting layer.

Example 5.A cellulose aceto -formate, having an acetyl content by weight of the total mixed cellulose ester of 18.5% and a formyl content of 13.0% (point V of the accompanying drawing), is dissolved in a mixture of acetone, water, butanone and dioxane, in a volume proportion of 40:15:10z35, respectively. In the known manner, this solution is coated on a metal casting drum. After drying, a film-forming layer, consisting of ethyl cellulose dissolved in a mixture of dichloromethane and ethanol in a volume-proportion of 90:10, respectively, is cast on the casting layer thus obtained. After sufiiciently drying, the high-gloss ethyl cellulose film is easily detached from the casting layer.

The above examples only serve to illustrate the invention which, for instance with respect to the'choice of the used solvents for the cellulose aceto-formate or the nature and the composition of the film-forming solutions, by no means is limited thereto. Thus, the film-forming solu tions among others may consist of cellulose esters, cellulose ethers, polyvinyl compounds or synthetic rubber compounds which may be dissolved in the -most difierent solvents. The cellulose aceto-formate casting layer may be used equally well in processes wherein the solvent of the filmforming layer is evaporated off as in processes wherein the coated film-forming layer is conducted through a precipitating bath.

I claim:

1. In a machine for casting of photographic film supports including means providing a casting surface, a casting layer coated on said surface consisting substantially of a cellulose acetoformate having an acetyl content by weight between 14.4% and 32% and a formyl content by weight between 3% and 15% on the total weight of the said cellulose aceto-formate, the total amount of the combined acetyl-formyl content being not more than about of that of fullyesterified cellulose.

2. In a machine for casting of photographic film supports including means providing a casting surface, a casting layer coated on said surface consisting substantially of a partially esterified cellulose aceto-formate having an acetyl content by weight of about 22.6% and a formyl content by weight of about 9% on the total weight of the said cellulose aceto-formate.

3. In a machine for casting of photographic film supports including means providing a casting surface, a casting layer coated on said surface consisting substantially of a partially esterified cellulose aceto-formate having an acetyl content by weight of about 19% and a formyl content by weight of about 4.5% on the total weight of the said cellulose aceto-formate.

4. In a machine for casting of photographic film supports including means providing a casting surface, a casting layer coated on said surface consisting substantially of a partially esterifled cellulose aceto-formate having an acetyl content by weight of about 16.5% and a formyl content by weight of about 13.0% on the total weight of the said cellulose aceto-iormate.

SERGE P. I-IENDRICX.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Name Date Seymour et a1. Nov. 21, 1944 Number 

1. IN A MACHINE FOR CASTING OF PHOTOGRAPHIC FILM SUPPORTS INCLUDING MEANS PROVIDING A CASTING SURFACE, A CASTING LAYER COATED ON SAID SURFACE CONSISTING SUBSTANTIALLY OF A CELLULOSE ACETOFORMATE HAVING AN ACETYL CONTENT BY WEIGHT BETWEEN 14.4% AND 32% AND A FORMYL CONTENT BY WEIGHT BETWEEN 3% AND 15% ON THE TOTAL WEIGHT OF THE SAID CELLULOSE ACETO-FRORMATE, THE TOTAL AMOUNT OF THE COMBINED ACETYL-FORMYL CONTENT BEING NOT MORE THAN ABOUT 80% OF THAT OF FULLYESTERIFIED CELLULOSE. 